SEASON FINALE - As the Legends are about to take off for their next destination, a massive timequake rocks the ship. In order to try and fix what has happened, they are forced to break the one cardinal rule of time travel. But if they are able to destroy the spear, they will face the ultimate consequence.

ARROW

Episode Title: S0519 "Dangerous Liaisons"

Oliver , Team Arrow, ARGUS and the SCPD kick off a citywide manhunt for Adrian Chase . Helix tells Felicity ) they have a way to find Chase but they will need something big, and illegal, from her in return.

Oliver (Stephen Amell) returns to the mayor's office and faces one of his most pressing issues yet - the forced release of dozens of violent criminals prosecuted by Adrian Chase (Josh Segarra). Meanwhile, a crate is delivered to Oliver's office containing a mysterious corpse encased in concrete.

SUPERGIRL

Episode Title: (#218) "Ace Reporter"

Lena's (guest star Katie McGarth) ex-boyfriend, Jack Spheer (guest star Rahul Kohli), comes to National City to unveil his big breakthrough in nano-technology, which has the potential to eradicate all diseases. Lena asks Kara to attend Jack's conference with her for support. When Kara sees Snapper (guest Star Ian Gomez) in attendance she's inspired to tap back into her reporter skills and questions Jack on his discovery, which ultimately leads to a bigger investigation that puts everyone in danger.

Episode Title: (#219) "Alex"

Alex (Chyler Leigh) is kidnapped and the kidnapper threatens to kill her unless Supergirl (Melissa Benoist) releases a notorious criminal from prison. Supergirl and Maggie (Floriana Lima) have always had different approaches to apprehending criminals but this time they must work together to save Alex. Meanwhile, Rhea (guest star Teri Hatcher) has an interesting proposal for Lena (Katie McGrath)

Episode Title: (#219) "City of Lost Children"

When an alien attacks National City, Supergirl (Melissa Benoist) and the DEO learn the alien is a Phorian, an otherwise peaceful race with telekinetic powers. Guardian (Mehcad Brooks) gets a lead on the Phorian's address but instead of finding the culprit, he finds a very scared boy named Marcus (guest star Lonnie Chavis). Marcus will only trust James so it is up to Guardian to stop the attacks on the city. Rhea's (Teri Hatcher) plan escalates.

THE FLASH

Episode Title: S0319 "The Once and Future Flash"

Barry (Grant Gustin) travels to the future to find out Savitar's still unknown identity in the hopes of saving Iris (Candice Patton). Upon his arrival in 2024, Barry encounters future versions of his Team Flash friends, who, following the death of Iris, have become very different people, profoundly impacted by their showdown with Savitar. It will be up to Barry to infuse a sense of hope back into the team, as he proves to be hero his future friends have been waiting for. Meanwhile, back in 2017, the hunt for Killer Frost (Danielle Panabaker) continues

Episode Title: S0320 "I Know Who You Are"

VIBE FACES OFF AGAINST KILLER FROST - Barry (Grant Gustin) and the team meet Tracy Brand (guest star Anne Dudek), a scientist, who may be the key to stopping Savitar. Unfortunately, Killer Frost (Danielle Panabaker) is also after Tracy so Team Flash must battle their old friend, which proves to be particularly difficult for Cisco (Carlos Valdes). Joe (Jesse L. Martin) and Cecile's (guest star Danielle Nicolet) relationship takes a big turn